Multimedia compositions, such as motion pictures, are often distributed in the form of digital multimedia files that contain video, audio, and related metadata content. Multimedia compositions often require multiple different versions in order to support multiple market segments, such as, for example, an airline version, a video-on-demand version, a cable or satellite television version, a DVD version, an OTT version, a promotional version, etc. Such multimedia compositions often include one or more video tracks, one or more audio tracks, and one or more metadata tracks. Depending on the type of multimedia composition, the metadata can include such things as subtitles, captioning, cropping instructions, color adjustments, dynamic range adjustments, or other information. Rather than creating multiple “master” copies of the multimedia composition, the multimedia composition can include sufficient video, audio, and metadata information to specify multiple versions.
One area where such multimedia compositions are used is in the delivery and manipulation of high dynamic range (HDR) content. Frequently, professional digital motion picture cameras are equipped to capture HDR images. For professional use, a few display devices, such as the Dolby Professional Reference Monitor, are capable of displaying HDR imagery. There is a growing list of consumer monitors that are HDR capable, including those manufactured by LG, Sony, Samsung, and others; however, most other display devices in existence are only capable of displaying Standard Dynamic Range (SDR) imagery.
Image manipulation, known as tone mapping, is applied to HDR material to reduce the dynamic range and make it suitable for display on SDR display equipment. The exact nature of the tone mapping manipulation is a creative decision that can be made on a shot-by-shot, or even frame-by-frame, basis. Separate tone mapping decisions may be created for different display devices. Each tone mapping decision is typically approved by the owners of the content or their agents to ensure fidelity to the artistic intent of the material.
There are a number of multimedia delivery formats in use or proposed that support HDR and related content.
Dolby Vision™ is a delivery format for organizing image media and sound media along with metadata such as tone mapping decisions. Dolby Vision is described in a white paper published by Dolby Laboratories available at https://www.dolby.com/us/en/technologies/dolby-vision/dolby-vision-white-paper.pdf on or before Sep. 28, 2017, the content of which are hereby incorporated by references in its entirety. While Dolby Vision was motivated by the desire to deliver HDR images along with approved tone mapping metadata, other types of metadata are also supported, including image cropping instructions, audio closed captioning, source timecodes, and other metadata. Systems, such as FLAME™ by Autodesk Inc., allow a user to perform a mastering processing by which an HDR graded reference is optimized to make the best use of the capacities of lower dynamic range displays. The mastering process generates an XML metadata file that is included along with the original HDR reference media as part of the Dolby Vision delivery package. A Dolby Vision compliant device is capable of accessing the image and sound media contained in the delivery package and applying the necessary metadata to properly display the material.
HDR10 is another HDR delivery format in common use. Like Dolby Vision, HDR10 includes a metadata track. Unlike Dolby Vision, HDR10 is considered a static system in that the metadata establishes picture settings at the beginning of the composition that remain constant throughout. An extended version of HDR10 referred to as HDR10+ has been proposed.
Hybrid-Log Gamma (HLG) is another HDR delivery format that is used primarily in broadcast (e.g., cable and satellite) delivery. HLG presents a single stream of content data that displays properly in both HDR and SDR monitors.
Technicolor HDR is yet another HDR delivery format this is used primarily in Europe.
Interoperable Master Format (IMF) is another multimedia delivery format that is specified by industry organization SMPTE (Society of Motion Picture and Television Engineers). As described on the Interoperable Master Format Forum website (www.imfforum.com), IMF is an international standard for the file-based interchange of multi-version, finished audio-visual works. It supports multi-language, multi-reel, subtitles/closed captions, video inserts and after-the-fact delivery of content with “supplemental packages.” IMF is built around a core framework (SMPTE ST 2067-2) that includes essence containers, audio and timed text essence formats, basic descriptive metadata, complex playlists, delivery, etc. This core framework is supplemented by incremental constraints (“applications”) specific to particular domains. A typical application will specify video codecs and image characteristics, and can specify additional descriptive metadata, for instance.